The assignee of the present application has previously proposed a multi-way reversing valve as that shown in FIG. 4 (see, for example, Patent Documents 1 and 2 mentioned below, the entire contents of each being herein incorporated by reference in their entirety). The illustrated multi-way reversing valve is briefly described below. It is noted that while a first fluid in/out port 12 and a second fluid in/out port 13 are drawn on the left and right of central axis O in FIG. 4 for easier comprehension, they are also provided in the layout shown in FIGS. 5A and 5B.
Multi-way reversing valve 10′ in the illustrated example is a rotary four-way reversing valve for use in a heat pump device. The multi-way reversing valve 10′ comprises a high-pressure fluid inlet port 11, the first fluid in/out port 12, the second fluid in/out port 13, and a low-pressure fluid outlet port 14, and a refrigerant is generally used for the fluid. The multi-way reversing valve 10′ includes a stepping motor 15 as a flow-path reversing actuator having a rotor 16 disposed on the inner-circumference side of a can 18 and a stator 17 that is externally fitted and fixed on the outer circumference of the can 18; a valve member 50 that is rotated by the stepping motor 15; and a valve housing 60 that rotatably holds this valve member 50.
It is noted that a planetary gear reduction system 40 is installed within the motor 15, and the rotation of the output shaft of the motor 15 (an output shaft 45 of the planetary gear reduction system 40) is transmitted directly to the valve member 50.
The valve housing 60 includes an upper box-like body (upper segment) 60A and a lower lid-like body (lower segment) 60B which are fastened in an airtight manner by means of three bolts 93. The upper box-like body 60A and the lower lid-like body 60B define a cylindrical valve chamber 61.
The upper box-like body 60A includes an upper base part 60a of a generally protruding shape, and a cylindrical wall part 60b that protrudes downward from the outer circumferential part of the lower surface of the upper base part 60a and that mainly defines a circumferential wall part of the valve chamber 61. The first fluid in/out port 12 and the second fluid in/out port 13, each having an inverted L-shaped section and comprising a horizontal hole and a vertical hole, are provided on the left and right of the upper base part 60a. Further, the low-pressure fluid outlet port 14 leading to the valve chamber 61 is provided on the front side of the upper part of the cylindrical wall part 60b. 
On the other hand, the lower lid-like body 60B is arranged in the shape of a thick plate with a ledge and onto which the lower end part of the cylindrical wall part 60b is fitted. In the center thereof (along rotational axis line O) is provided the high-pressure fluid inlet port 11 which penetrates therethrough and opens into the valve chamber 61. It is noted that in order to reduce weight and so forth, aluminum is typically used for the material of the valve housing 60 (i.e., the upper box-like body 60A and the lower lid-like body 60B).
A valve seat member 65 is provided (screwed) at the ceiling part of the valve chamber 61. The respective lower end openings of the first fluid in/out port 12 and the second fluid in/out port 13 are formed in the valve seat member 65.
The valve member 50 includes a valve shaft member 50A made of stainless steel (SUS) comprising, in order from the top, a small-diameter shaft part 51 that is coupled with, in an integrally rotatable manner, the output shaft 45 of the planetary gear reduction system 40 within the motor 15, a center shaft part 52 inserted into a center hole 67 formed in the upper box-like body 60A and into an opening 69 formed in the center of the valve seat member 65, and a large-diameter cylindrical shaft part 53 inserted into the high-pressure fluid inlet port 11; and an off-axis member 54 that is externally fitted and fixed onto a ledge part of the valve shaft member 50A, the ledge part spanning from the lower end part of the center shaft part 52 located within the valve chamber 61 down to the upper end of a center thick-walled part 53a of the large-diameter cylindrical shaft part 53. The parts of the valve member 50 located within the valve chamber 61 (i.e., the lower part of the center shaft part 52, the large-diameter cylindrical shaft part 53, and the off-axis member 54) form a crank-shaped or inverted L-shaped reversing valve member part 50B.
The center shaft part 52 and the lower end part of the large-diameter cylindrical shaft part 53 of the valve shaft member 50A are respectively supported by sleeve-like shaft bearing members 81 and 82 in a slidable and rotatable fashion. Further, a Teflon (registered trademark) lip seal 83 is installed between the lower tapered surface part of the center thick-walled part 53a of the large-diameter cylindrical shaft part 53 and the inner circumferential surface of the high-pressure fluid inlet port 11.
A valve member internal passage 55 is provided within the reversing valve member part 50B, the valve member internal passage 55 being of a crank-shape or an inverted L-shape similar thereto.
At the exit-side end part of this valve member internal passage 55, an O-ring 74 and a square ring 75 as seal members are mounted so as to be in pressured contact with the valve seat member 65 in an airtight manner. The O-ring 74 is pressured radially outward by the high-pressure fluid flowing through the valve member internal passage 55, and its cross-section changes from circular to elliptical. Utilizing this change in shape of the O-ring 74, one end surface of the square ring 75 is pressed against the valve seat member 65 to attain a sealing effect.
It is noted that, in order to press the exit-side end part of the valve member internal passage 55 (i.e., the square ring 75) against the valve seat member 65, a coil spring 92 that biases the valve member 50 upward is compressed and loaded around the outer circumference of a cylindrical protruding wall part 60d that is provided in a protruding manner at the center part of the upper surface of the lower lid-like body 60B. In addition, in order to prevent any unwanted fluid leakage, a seal member, such as an O-ring 95, etc., is mounted at key points, such as at interfaces between the various members, etc., for example, between the lower inner circumferential surface of the cylindrical wall part 60b of the upper box-like body 60A and the upper outer circumferential surface of the lower lid-like body 60B.
With the multi-way reversing valve (four-way reversing valve) 10′ having the configuration above, as the valve member 50 is rotated by the motor 15, and the exit-side end part of the valve member internal passage 55 (i.e., the square ring 75) arrives at the position directly below (the lower end of) the first fluid in/out port 12 of the valve seat member 65 (i.e., the state shown in FIG. 5B), the high-pressure fluid inlet port 11 and the first fluid in/out port 12 are placed in communication with each other via the valve member internal passage 55. Thus, the high-temperature high-pressure fluid flows towards the first fluid in/out port 12 via the valve member internal passage 55, while the low-temperature low-pressure fluid from the second fluid in/out port 13 flows towards the low-pressure fluid outlet port 14 via the valve chamber 61.
Conversely, as the exit-side end part of the valve member internal passage 55 (i.e., the square ring 75) is rotated to the position directly below (the lower end of) the second fluid in/out port 13 of the valve seat member 65 (i.e., the state shown in FIG. 5A), the high-pressure fluid inlet port 11 and the second fluid in/out port 13 are placed in communication with each other via the valve member internal passage 55. Thus, the high-temperature high-pressure fluid flows towards the second fluid in/out port 13 via the valve member internal passage 55, while the low-temperature low-pressure fluid from the first fluid in/out port 12 flows towards the low-pressure fluid outlet port 14 via the valve chamber 61.
Thus, the multi-way reversing valve 10′ in the illustrated example reverses flow paths by rotating the valve member 50 to selectively place either the first fluid in/out port 12 or the second fluid in/out port 13 in communication with either the high-pressure fluid inlet port 11 or the low-pressure fluid outlet port 14 via the valve member internal passage 55 and the valve chamber 61. See, e.g., Patent Document 1 (JP Patent Application No. 2010-010309) and Patent Document 2 (JP Patent Application No. 2009-203926).